Spacer bar and die cleaner mechanism for strip welder



7, 1956 M. M. SEELOFF ETAL 2,758,184

SPACER BAR AND DIE CLEANER MECHANISM FOR STRIP WELDER Filed May 5, 19525 Sheets-Sheet 1 INVENTORS MELVIN M. SEELOFF ROBERT ANDERSON BY W ATTRNEY g- 7, 1956 M. M. SEELOFF ETAL 2,758,184

SPACER BAR AND DIE CLEANER MECHANISM FOR STRIP WELDER Filed May 5, 19523 SheetsSheet INVESTORS MELVIN M. SEELOFF ROBERT ANDERSON INVENTORSSEELOFF 3 Sheets-Sheet 3 I a Q r k fig MELVIN M ROBERT ANDERSON BY j m WX ATT RAEY M M. SEELOFF ET AL PACER BAR AND DIE CLEANER MECHANISM FORSTRIP WELDER Aug. 7, 1956 Filed May 5, 1952 United te i aten SPACER BARAND DIE CLEANER MECHANISM FOR STRIP WELDER Melvin M. Seelotf and RobertAnderson, Warren, Ohio,

assignors to The Taylor-Winfield Corporation, Warren, Ohio, acorporation of Ohio Application May 5, 1952, Serial No. 286,041

Claims. (Cl. 219 -4) The present invention relates to electricresistance flash-butt welding, and more particularly to improvedapparatus for use in flash-butt welding of steel sheet and strip, forexample, in continuous metal processing lines.

The invention seeks to provide an improved mechanism and mode ofoperation for aligning and spacing contiguous ends of strip prior towelding together of the same, and for cleaning weld fiash from the stripclamping die members between strip Welding operations.

In connection with the above it is a more specific object of thisinvention to provide an improved and simplified spacer bar and diecleaner apparatus adapted for accurately guided vertical movementbetween spaced strip clamping die members whereby accurate spacing ofthe metal strip is assured and cleaning of the welding dies isaccomplished in a most practical and effective manner. The use ofcombined spacer bar and die cleaner assemblies in strip welding is ofcourse well known and the same is thus not asserted as a part of thisinvention, but rather our contribution resides in a novel constructionand mode of operation of welding apparatus whereby spacer bar assembliesof a known general type may be utilized with accuracy and efiectivenessheretofore unobtainable.

Another object of the present invention is the provision of a spacer barand die cleaner assembly adapted for repeated insertion between weldingdie members for the purpose of cleaning welding flash therefrom andaccurately spacing contiguous ends of successive sheets or stripswherein certain arange'ments are incorporated for maintaining die anddie cleaner wear at an absolute minimum.

Yet another object of this invention is the provision of a spacer barassembly of the character described wherein adjustable strip end spacingis afforded by means of a plurality of parallel gauging faces ofgraduated thickness rather than by means of tapering gauge faces as hasbeen heretofore commonly practiced. Tapered gauge faces have been foundundesirable for welding thin strip and sheet material since turning upof the metal often occurs in the spacing operation causing misalignmentof the strip ends and accordingly providing an inferior weld. By ourarrangement turning up of the strip ends is avoided while substantiallythe same spacing adjustment may be provided by utilizing a large numberof graduated steps on the spacer bar.

Spacer bars with parallel gauge faces have heretofore been thought to beimpractical since, in order to withdraw the bar after spacing the stripends, the die members should be backed off slightly to prevent turningup of the strip ends and undue wear upon the spacer bar. The presentinvention accordingly seeks to provide a novel arrangement for backingoff the movable die members after spacing of the strip ends and beforewelding thereof whereby the use of a stepped spacer bar may be renderedconsistent with the general objectives of speed in operation andaccurate control of the movable die "members during all phases of thewelding procedure.

Specifically the above object contemplates the use of a pair of or pairsof series connected actuating members one of which is arranged toactuate the movable die members independently of the other actuatingmember for spacing the strip ends, and the other of which is arranged todrive the movable die members during the flashing and upset operationsthrough a direct connection with the die members. As will be readilyunderstood upon consideration of the description to follow ourarrangement provides for a speedy and accurate back ofi? of the movabledie members to release the stepped spacer bar but does not adverselyaffect the normal operation of the apparatus.

The above and other objects and advantages of our invention will becomeapparent upon full consideration of the following detailed specificationand accompanying drawings wherein is illustrated :a certain preferredembodiment of our invention.

In the drawing:

Figure 1 is a fragmentary side elevation of a flash-butt strip welderconstructed in accordance with the teachings of our invention;

Figures 2-5 are fragmentary section views of the apparatus of Figure 1illustrating the same in various operating positions; and

Figures 68 are fragmentary section views of the apparatus of Figure 1showing particularly our novel arrangement for controlling the movementof the welder dies.

In Figure 1 the reference numeral 10 designates a fixed machine baseupon which is mounted, in accordance with usual welding practice, afixed platen 11 and movable platen 12. Fixed platen 11 is secured to thebase 10 in normally fixed relation but may be provided with conventionaladjustments, not shown, for obtaining proper strip alignment. Theillustrated apparatus contemplates the accommodation of strip of widthsin excess of fifty to sixty inches, and accordingly platen 11 comprisesa pair of spaced upstanding frame members 13 whereby the strip, notshown, may pass longitudinally of the welding apparatus, or for examplein a direction from platen 12 to platen 11, between the spaced framemembers 13. A pair of die members 14 and 15 are carried by the fixedplaten 11 for clamping the end portion of a strip to be welded, and itwill be understood that the apparatus of Figure 1 includes such controland structure as is necessary to apply adequate clamping pressurebetween the die members 14 and 15. A preferred structure for thispurpose is disclosed in our copending related application Ser. No.282,766, filed April 17, 1952, entitled Work Holding Apparatus forFlash-Butt Welding Machines, now U. S. Patent 2,710,903, granted on June14, 1955.

Movable platen 12 is constructed similarly to the ifixed platen 11,including spaced upstanding frame members 16 and upper and lower diemembers 17 and 18, and is conventionally mounted on base 10 for slidablemovement toward and away from the fixed platen 11.

Normal operation of flash-butt welding apparatus of the type hereinillustrated comprises a first step of positioning platen 12 apredetermined distance from the fixed platen 11. The trailing andleading end portions of two successive coils or sheets are then properlyspaced relative to the platens 11 and 12 whereupon die members 14 and15, and 17 and 18 are caused to close to firmly clamp the end portionsin the desired relation. The actual welding operation may then becarried out by causing electric current to pass through the contiguousend surfaces of each of the strips or coils while effecting suitableadvancing or closing movement of the movable platen 12 in the directionof the fixed platen 1'1.

One feature of our invention relates to improved apparatus for spacingthe trailing and leading ends of successive coils and the followingdescription of such apparatus may be facilitated by reference to Figures1 through 5.

Our invention teaches the use, for the purpose of spacing adjacent stripends, of a spacer bar member 19 having a plurality of parallel gaugingfaces thereon, each of a different gauging thickness. In the preferredmode of operation spacer bar 19 is disposed vertically and is insertedbetween the fixed and movable platens 11 and 12 as shown in Figure 4,for example, whereby upon subsequent movement of strips and 21 towardeach other the end surface of each of the strips will abut oppositegauge faces of the spacer bar 19 and will accordingly be maintained in apredetermined separation. It will be understood that prior to theinsertion of spacer bar 19 platens 11 and 12 are properly prepositionedin a work loading position, and thus when the strips 20 and 21 abut thespacer bar 19 the cooperating die members of each platen may be closedunder pressure to properly clamp the strip ends in readiness for awelding operation.

Spacer bar 19 is rigidly secured at its upper end to a verticallydisposed carrier member 22 which is adapted in a manner to besubsequently described to support and guide the bar 19 in movement toand from gauging and retracted positions. Pivotally secured to the upperend of carrier member 22 is a short link 23 which is in turn pivotallysecured to a lever arm 24. Lever arm 24, as shown in Figure l, ispivotally mounted on the fixed platen 11 by means of a shaft 26, and itwill be readily observed that pivotal movement of the lever arm 24 willcause carrier member 22 and spacer bar 19 to be moved vertically upwardor downward and also horizontally to a certain extent due to thepresence of a horizontal component in the arcuate movement of the lever24.

While the present description refers to a single lever arm 24 andcarrier 22, it will be understood that a spaced bar of such arms andcarriers is preferably provided, i. e., one at each end of the spacerbar 19, and

that a larger number may be utilized if desired where unusually widestrip or sheet metal is to be accommodated. Where more than one leverarm and carrier are utilized suitable interconnecting means may beprovided to synchronize the movement thereof as will be readilyappreciated.

Lever arm 24 is motivated by means of a conventional fluid operatedactuating device 25, the cylinder part of which is mounted on the framemember 13 while the piston rod is connected to the lever arm 24outwardly of the point of pivotal mounting thereof. By suitableapplication of fluid presssure to the actuator 25 lever arm 24 may becaused to pivot in a clockwise or counterclockwise direction as may bedesired.

Secured to each end of the spacer bar member 19 is a guide bar 27 whichis preferably slightly wider than the spacer bar 19 and extends belowthe lower end extremity thereof. For cooperation with the guide bars 27we have provided at each end corner of each of the die members 14-18 ahardened guide block 28. Thus, by appropriate prepositioning of themovable platen 12 with respect to the fixed platen 11 preparatory toinserting therebetween spacer bar 19, the latter may be provided withaccurate and rigid guidance in vertically upward or downward movement.The position of the movable platen 12 wherein guide blocks 28 areproperly separated for the insertion and accurate guidance of guide bars27 is commonly referred to as the work loading position, and wheredesired, suitable automatic control means may be incorporated into thewelding apparat us to so position the movable platen 12 after eachwelding operation.

It will be noted in. respect to the. vertically guided movement of thespacer bar 19 that while movement of the lever arm 24 is purely arcuatethe link member 23 permits movement of the carrier 22 in a horizontaldirection with respect to the point of suspension thereof from the leverarm 24. This will be apparent from comparison of Figures 3 and 4.

The rigid and accurate guidance of spacer bar 19 atforded by the guidebars 27 and blocks 28 is advantageous in two important respects. First,feeding of the strip ends into gauging contact with the spacer bar 19 iscommonly accomplished by means of pinch rolls 29 and 30 which arenecessarily inertia laden. By rigidly restraining the bar 19 we preventits being misaligned by impact thereagainst of the inwardly movingstrip. Secondly, we have found it desirable to incorporate in thegauging apparatus means for trimming weld flash and other foreign matterfrom the adjacent faces of the die members and electrode bars 31 andpressure bars 31 mounted thereon. Thus, by accurately guidingthemovement of the spacer bar 19 we have been able to mount thereon apair of horizontally disposed cutter bars 32 which are so arranged as topass over the faceof the die members 14-18 and electrode and pressurebars 31 and 31 during downward movement of the spacer bar 19.

According to the teachings of the invention spacer bar 19 and thesupporting and operating elements therefor are so proportioned thatlever arm 24 is approximately horizontally disposed when the spacer bar19 is in a gauging position, but is directed substantially upward fromthe horizontal when spacer bar 19 is withdrawn upwardly into a retractedposition. The asrangement is such that the point of suspension ofcarrier 22 is moved substantially to the left as shown in Figure 2, andaccordingly spacer bar 19 hangs therefrom in a position substantially tothe left of the point of meeting of the strip sections to be welded. Thespacer bar is thereby protected from direct impingement of flash duringthe welding operation. Maintenance time on the spacer apparatus is thusreduced to a practical minimum.

In moving the spacer bar 19 from a retracted and inoperative position asshown in Figure 2 to operating position between platens 11 and 12 it isimportant that the bar 19 be properly inserted between the guide blocks28 so that the guide bar 27 will not bind during the initial stages ofthe insertion. To this end we have provided a keyway 33 in carrier 22which is adapted for cooperating engagement with a key 34 which isrigidly mounted on the fixed platen 11. For a purpose which willsubsequently be disclosed, keyway 33 is somewhat wider than is key 34 sothat carrier 22 may be loosely guided thereby in its vertical movement.

As will be apparent from the drawing, the key 34 is so oriented on thefixed platen 11 that engagement thereof with the keyway 33 in carrier 22begins during the initial insertion of the guide bar 27 between blocks28. Thus the apparatus is provided with additional guidance until guidebar 27 engages the lower blocks 28 whereupon guidance is providedsubstantially wholly by blocks 28 and bar 27. Bar 27 is preferablytapered at its lower end portion to facilitate initial entry into theupper guide blocks 28.

After spacer bar 19 is initially inserted between platens 11 and 12 itis caused to move, by continued application of fluid pressure to theupper end of actuator 25, to a fully downward position as shown inFigure 3. When the apparatus has reached this position cutter bars 32have moved completely across the faces of the lower electrode bars 31and the pressure bars 31 and the same are thereby free of interferingflash particles and are in readiness for a new welding operation. Fluidis then applied to the lower end of actuator 25 to cause lever arm 24 tomove upwardly a predetermined distance to position one of the pluralityof gauge faces of the spacer bar 19 opposite electrode bars 31 andpressure bars 31'. Motive power is then applied to pinch rolls 29 and 30to cause strip sections to move inwardly from both directions toward thegauge faces of bar 19, and the pinch rolls are of course stopped whenthe inwardly moving strip sections abut the spacer bar. Upon subsequentremoval of the bar 19 to its retracted and protected upper position thewelding operation may proceed by appropriate inward movement of platen12 and application of welding energy to the electrode bars 31.

Successful use of a spacer bar having parallel rather than tapered gaugefaces requires that the platens 11 and 12 be slightly separated beforethe spacer bar is withdrawn to relieve the pressure exerted thereon bythe clamped strip sections. This is particularly important where thinstock is to be welded inasmuch as the frictional drag of the endsurfaces of the strip upon the gauge faces tends to cause upward turningof the strip endsthe occurrence of which would be prohibitive tocarrying out a satisfactory welding operation. Such separation is alsodesirable to prevent unnecessary wear upon the gauge face as will bereadily understood.

To permit platens 11 and 12 to be slightly separated for Withdrawal ofthe spacer bar 19 while maintaining operation of the apparatusconsistent with the general objectives of speed and accuracy of platenmovement we have provided a novel actuating arrangement for the movableplaten 12, which arrangement is illustrated in Figure l, andschematically in Figures 6-8. Referring particularly to the schematicrepresentations in Figures 68 it will be observed that the piston member35 of a small diameter short stroke hydraulic actuator 36 is rigidlyconnected to the movable platen 12 by means of a bracket 37. Preferablythe piston 35 is substantially aligned horizontally with the pass lineof the strip sections to be welded whereby forces applied to the platen12 will be properly balanced. And it will be understood that movingforce is preferably applied to each side of the platen 12 by duplicateactuating devices positioned in straddling relation to the strip. Thisis in accordance with usual strip Welder construction.

Rigidly connected to the cylinder of actuator 36 is the piston rod 38 ofa large diameter relatively long stroke hydraulic actuator 39, knownconventionally as an upset cylinder. In the illustrated apparatus apiston rod 38 extends outwardly of both ends of the upset cylinder 39and is provided with means, such as adjustable bucking nuts 40 and 41,for limiting movement of the rod 38 in either longitudinal direction.Nut 40 may be used, for example, to normally limit retracting movementof movable platen 12 to movement into the work loading position, whilenut 41 may be used to control the final die opening or the ultimatespacing of the die members at the end of the welding operation. Nut 41particularly should be readily adjustable to provide upset adjustmentfor strip sections of various thicknesses. A preferred arrangement forproviding upset adjustment is fully disclosed in our co-pending relatedapplication Ser. No. 286,042, filed May 5, 1952, entitled Die SpacingMeans For Welding Apparatus, now U. S. Patent No. 2,63 6,966, issuedApril 28, 1953.

As will be observed in Figures 6-8, the right hand end of actuator 36 isprovided internally with a circular land or abutment against whichpiston 35 is adapted to rigidly bottom upon application of fluidpressure to the rod end of actuator 35 through conduit 42. According tothe principles of the invention, fluid pressure is applied to the smallactuator 35 substantially at all times through conduit 42, andaccordingly, when pressure is applied to the head end of actuator 39through conduit 43 force is transmitted to the movable platen 12 by adirect and rigid rnetal-to-metal contact through the small actuator 36.Thus the necessarily large upset pressures may be applied independentlyof the actuator 36 in the manner illustrated in Figure 8.

At the end of a welding operation fluid pressure may be appliedsimultaneously to actuators 36 and 39 through conduits '44 and 45respectively, causing piston rod 38 and actuator 36 to move to the rightand piston 35 to move to the left with respect to actuator 36. Upon thenut 40 reaching its limit stop, as shown in Figure 6, furthermovement-of piston rod 38 to the right is prevented and movement ofpiston 35 to the left with respect to the actuator 36 is positivelylimited as piston 35 hottoms against the left hand end of the actuator.It should thus be apparent that by proper adjusment of nut 40 we mayprovide that with actuators 36 and 39 conditioned as shown in Figure 6the movable platen 12 will be accurately positioned in the work loadingposition. Cleaning of the-dies, and feeding and spacing of theworkpieces may then be effected in the manner previously described.

With the workpieces properly spaced and clamped, fluid pressure may beapplied to conduit 42 leading into the left hand end of actuator 36.Piston 35, and movable platen 12, are thereby caused to move to theright until the piston 35 bottoms at the right hand end of actuator 36,whereupon the connection between piston rod 38 and the movable platen 12will again be direct and rigid. In this operation all pressure isrelieved from the spacer bar 19 and from the guide bars 27 therefor, andthe same may be moved into a retracted position by application of fluidpressure to the lower end of actuator 25.

It is contemplated that the piston 35 will have a relatively shortoperating stroke, as for example one or two inches, and that the fluiddisplacement required in moving the piston 35 through its full operatingstroke will be extremely lowsufiicient only to overcome the slidingfriction of the apparatuswhereby the short retracting movement of theplaten 12 may be carried out in a minimum of time.

As a further means of preventing unnecessary wear upon the gauge facesof spacer bar 19 and/ or mutilation of the end portions of thinworkpieces, we have provided a novel arrangement whereby the spacer bar19, upon platen 12 being moved into a retracted position as in Figure 8,is caused to swing outwardly of the platen 11 to a positionsubstantially centrally intermediate the fixed and movable platens 11and 12.

As illustrated in Figure 4, lever arm 24 is so proportioned that itspoint of pivotal connection with link 23 (point A) lies to the right tothe point of pivotal connection of the link 23 with carrier 22 (point B)at all times when spacer bar 19 is positioned so as to present a gangingface at the pass line of the strip sections 26 and 21. Although Figure 4illustrates the use of the widest gauge faces only, the above fact maybe readily ascertained by noting that point A will continue to moveoutwardly a slight amount as the spacer bar 19 is raised to present newgauging faces to the pass line. Point B is of course confined tomovement along the vertical longitudinal axis of the spacer bar 19 byvirtue of the heretofore described guiding means provided for the spacerbar 19.

Thus, it will be apparent that upon releasing movement of the movableplaten 12 by application of fluid pressure through conduit 42, spacerbar 19 will, by the action of gravity, tend to move outwardly of themovable platen 11 and thus away from the die members 14 and 15 thereof.By providing a certain measure of looseness between key 34 and keyway 33provided in the carrier 22 we have provided that the spacer bar 19 mayswing by gravity to a point substantially centrally intermediate theseparated platens 11 and 12, as shown in Figure 5, from which positionthe bar 19 may be withdrawn into a retracted position without contactingthe end surfaces of either of the clamped strip sections 20 or 21.

In the preferred construction of the apparatus keyway 33 and key 34 areso dimensioned that contact is made between one surface of the keyway 33and key 34 when the bar 19 is vertically guided by means of guide bar 27and blocks 28, and contact is made between opposite 7 surfaces ofmembers 33 and 34 to limit outward swinging movement of the bar 19 to aposition spaced from both platens 11 and 12.

The advantages of our invention should now be apparent. We have provideda wholly practical arrangement for utilizing a strip spacing memberhaving a plurality of stepped pairs of parallel gauge faces whereby afiat abutment is afforded for contact by inwardly moving strip sections.Heretofore slightly tapered gauge surfaces have been commonly providedwhereby upon a short withdrawal movement of the spacing or gaugingmember the gauging surfaces were automatically drawn away from the endsurfaces of the strip sections. We have found such tapered surfaces tobe undesirable, however, par ticularly for thin material since a skewedcontact with the strip ends is inherent in such apparatus, and a slightturning-up of the end portions of the material inevitably results. Ourinvention, on the other hand, teaches the use of parallel gaugingsurfaces with a novel arrangement for rapidly withdrawing the movableplaten 12 whereby the spacer bar 19 moves away from the end surfaces ofthe strip and may be readily withdrawn into a retracted position.

By providing large and small platen actuating members, arranged inseries relation and independently operable, the movable platen 12 may bequickly retracted for removal of the spacing bar 19, and it is importantto note that the upset cylinder 39 remains wholly unaffected during suchretraction. While the upset cylinder must necessarily be of largediameter to properly carry out the welding operation, the seriesconnected actuator 36 may be of small diameter and short stroke wherebythe same may be operated in a practical minimum of time from a hydraulicpower source of normal capacity. Our arrangement further provides thatduring the flashing and upset portions of a complete welding cycle adirect and rigid connection exists between the upset cylinder 39 and themovable platen 12 through the interposed actuator 36.

In addition to the above features, we have provided a novel arrangementfor controlling and guiding the movement of spacer bar 19 whereby properinsertion of the same between the platens 11 and 12 is assured andwhereby rigid support is at all times provided when the bar is ingauging position so that the impact of incoming strip does not cause thebar to become misaligned.

To prevent unnecessary wear upon the accurately dimensioned gaugingsurfaces of spacer bar 19 we have provided a novel supporting meanstherefor, including link 23, whereby when spacer bar 19 is in gaugingposition it is urged outwardly of the fixed platen 11 by the action ofgravity. Thus upon subsequent retraction of the movable platen 12 bar 19moves away from the strip end and may be rapidly withdrawn without wearupon the gauge surfaces or damage to the end surface of the strip.Loosely fitting keyway and key members positioned on carrier 22 andplaten 11 respectively coopcrate to position the spacer bar 19substantially centrally intermediate the separated platens 11 and 12 sothat pendulum action of the pivotally suspended carrier and spacer baris prevented.

KeyWay 33 and key 34 also serve an additional function of providing apreliminary approximate guide for the carrier 22 as the same is causedto move downwardly from a fully retracted position and it will beunderstood that this aids materially in the proper initial insertion ofthe spacer bar 19 between the platens 11 and 12.

Our construction, permitting the use of more accurate and rigid guidemeans for spacer bar 19, renders the same more suitable for use incarrying cutter bars for cleaning flash and other foreign matter fromthe die faces since rigid and sharp cutters may be utilized withoutcausing damage to the die faces.

It should be understood, however, that the apparatus herein specificallydescribed represents but a single application of the teachings of ourinvention and should be considered as illustrative only thereof.Reference should therefore be had to the appended claims in determiningthe true scope of the invention.

We claim:

1. In a flash-butt welding machine of the type having a fixed andmovable platen and relatively movable dies carried by each of saidplatens for clamping therebetween workpieces to be Welded; thecombination of a lever arm pivotally mounted on said fixed platen, powermeans connecting said lever arm for causing pivotal movement thereof, alink pivotally secured to said lever arm outwardly of the point ofpivotal mounting thereof and gen.- erally above said dies, a carrierpivotally secured to said link and suspended freely therefrom, a spacerbar rigidly connected to said carrier and having a plurality of pairs ofparallel gauging faces thereon disposed generally parallel with saiddies, said lever arm being pivotable into an upper limit positionwherein said spacer bar is positioned above and substantially to oneside of said dies, guide members positioned in said dies, guide meanscar ried by said spacer bar adapted when said platens are positioned ina predetermined separation to coact with said guide members to rigidlyconfine movement of said spacer bar between said platens to a verticaldirection, cooperating key and keyway means on said fixed platen andsaid carrier adapted to initially guide said spacer bar in movement fromsaid upper limit position to a positon between said platens, and meansto retract said movable platen from said position of predeterminedseparation, said lever arm and said link being so arranged that saidspacer bar is caused to move outwardly of said fixed platen by theaction of gravity upon said movable platen being so retracted, said keyand keyway being loosely fitting whereby said spacer bar may moveoutwardly of said fixed platen a predetermined distance.

2. In a flash-butt welding machine of the type having a fixed andmovable platen and relatively movable dies carried by each of saidplatens for clamping therebetween workpieces to be welded; thecombination of a lever arm pivotally mounted on said fixed platen, powermeans connecting said lever arm for causing pivotal movement thereof, alink pivotally mounted to said lever arm outwardly of a point of pivotalmounting thereof and generally above said dies, a spacer bar pivotallyconnected with said link and having a plurality of pairs of parallelgauging faces thereon disposed generally parallel with said dies, rigidguide means on said spacer bar and said platens adapted to rigidly guidemovement of said spacer bar between said platens when said platens arepositioned in a predetermined separation, and means to retract saidmovable platon from said position of predetermined separation, saidlever arm and said link being so arranged that said spacer bar is causedto move outwardly of said fixed platen by the action of gravity uponsaid movable platen being so retracted.

3. In a flash-butt welding machine of the type having a fixed andmovable platen and relatively movable dies carried by each of saidplatens for clamping therebetween workpieces to be welded; thecombination of a spacer bar having parallel gauge faces thereon, meansto move said spacer bar into and out of an operative position betweensaid platens whereby to effect a predetermined spacing of saidworkpieces when said platens are in a work loading position, means tomove said movable platen comprising i a first bodily movable smalldiameter short stroke hydraulic actuator, a second large diameterhydraulic actuator, said first actuator including a piston part and acylinder part, one of said parts being connected to said movable platen,said second actuator including a movable member, said movable memberbeing connected to the other of said first actuator parts, and separateand independent hydraulic power supplies for said actuators.

4. Apparatus according to claim 3 further characterized by said firstactuator being so constructed that when fully retracted said piston partis in direct contact with said cylinder part whereby upon application ofpressure to the movable member of said second actuator said pressure istransmitted directly to said movable platen.

5. In a flash-butt welding machine of the type having a fixed andmovable platen and relatively movable dies carried by each of saidplatens for clamping therebetween workpieces to be welded; thecombination of a spacer bar having parallel gauge faces thereon, meansto move said spacer bar into and out of operative position between saidplatens whereby to efiect a predetermined spacing between saidworkpieces when said platens are in a work loading position, means tomove said movable platen comprising a pair of series connected first andsecond actuating members, said first actuating member being bodilymovable and being connected to said movable platen and said secondactuating member being connected to said first actuating member, andpower means to operate said first and second actuators independently,said first actuator being of the low power quick acting type, and saidsecond actuator being of the high power type.

6. Apparatus according to claim 5 further characterized by means tolimit the retracting movement of said second actuator in a direction tocause separation of said platens whereby upon said second actuator beingfully retracted to said limit position and said first actuator beingfully extended said platens are in a work loading position.

7. Apparatus according to claim 6 further characterized by means torigidly limit the retracting movement of said first actuator wherebyupon such retracting movement said second actuator is effectivelydirectly coupled with said movable platen to apply force thereto in aclosing direction.

8. In a flash-butt welding machine of the type having a fixed andmovable platen and relatively movable dies carried by each of saidplatens for clamping therebetween workpieces to be welded, thecombination of a spacer bar adapted to be inserted between said platensfor spacing apart the end edges of pieces to be welded together, saidspacer bar having a plurality of pairs of parallel gauging facesthereon, means to move said platens into a position of predeterminedseparation prior to the insertion between said platens of said spacerbar, means to withdraw the movable one of said platens a predetermineddistance following a gauging operation to increase said spacing, meansoperative upon said movable platen being withdrawn as aforesaid to causesaid spacer bar to move outwardly of said fixed platen a distance lessthan the distance said movable platen is withdrawn whereby said parallelgauging faces are clear of strip end portions gripped by said platenwhen said spacer bar is withdrawn.

9. Apparatus according to claim 8 further characterized by said lastmentioned means comprising a lever arm pivoted on one of said platens,and a free link interconnecting said lever arm and said spacer bar, saidlever arm being operative to lower said spacer bar into gauging positionand being of such length at the point of interconnection with said linkthat said point is positioned outwardly of said spacer bar when thelatter is in gauging position.

10. In a flash-butt welding machine of the type having a fixed andmovable platen and relatively movable dies carried by each of saidplatens for clamping therebetween workpieces to be welded, thecombination of a spacer bar adapted to be inserted between said platensfor spacing apart the end edges of pieces to be welded together, saidspacer bar having a plurality of pairs of parallel gauging facesthereon, means on said platens to hold said spacer bar in a verticalposition upon movement of said spacer bar and said movable platen intogauging position, means to urge said spacer bar outwardly of said fixedplaten, and means to withdraw said movable platen from gauging position,said means to urge being thereupon operative to move said spacer baroutwardly of said fixed platen a distance less than the withdrawingmovement of said movable platen whereby said spacer bar may be freelyraised vertically from gauging position.

References Cited in the file of this patent UNITED STATES PATENTS741,146 Labofish Oct. 13, 1903 1,879,217 Hanson Sept. 27, 1932 2,002,007Hanson May 21, 1935 2,203,151 Iverson June 4, 1940 2,443,311 Ernst June1, 1948 2,636,966 Seeloff Apr. 28, 1953 FOREIGN PATENTS 654,601 GreatBritain June 20, 1951

